Questions tagged [udp]

For questions about User Datagram Protocol, a Transport Layer protocol.

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Does the OSI model support connectionless communication in the transport layer? [closed]

In section 7.4.4.1.2 of ISO/IEC 7498-1:1994(E) it begins with: In connectionless-mode, the Transport Layer provides the following functions to support connectionless-mode transmission: But many ...
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1answer
470 views

How does the UDP Checksum tell me if my data has changed?

currently I am having a Computer Networking cours and I am reading "Computer Networking a Top-Down Approach" At this point I am reading the Transport Layer part. And I have read about the checksum ...
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1answer
531 views

UDP checksum calculation on improperly padded packets

Suppose I'm receiving IPv4 UDP packets whose payload is less than 18 octets, so when they are transmitted over Ethernet they have some trailing padding. Between the packets' source and my receiver ...
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1answer
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Traceroute UDP port question

I know, that traceroute uses UDP, and for destination port it starts with 33434. Then, with each next hop it increments the destination port number by 1. The questions is: why does traceroute need to ...
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5answers
2k views

Why is TCP/IP popular?

I understand that TCP/IP protocol is widely used as it is more secure (the third handshake). But, is there any other reason why TCP/IP is more popular than UDP?
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2answers
931 views

Why do open ports give no response in networking?

Nmap places ports in open|filtered state when it is unable to determine whether a port is open or filtered. This occurs for scan types in which open ports give no response. The lack of response could ...
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1answer
276 views

Does an EIM-NAT work across both UDP and TCP?

I've read RFC 4787, 5382 and 5128 and I just need a bit of clarification. Assume a NAT has Endpoint Independent Mapping behavior for both UDP and TCP. Although I understand that if a machine would ...
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2answers
367 views

Traceroute program that does not rely on ICMP echo requests?

Is there any Traceroute program that does not rely on ICMP echo requests? The question is very straight forward, and I can't get into more details at the moment.
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1answer
4k views

Iperf results on UDP Bandwidth

I am currently testing iperf with a view to automating some testing servers for our company. To do this I am using an iperf server in the cloud which is well connected and is only 5 hops away from ...
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2answers
86 views

Limiting NIC speed leads to better video quality

I have two workstations A and B connected to the same L3 switch at 1Gbps. Workstation A generates an MPEG2-TS UDP video stream at 10Mbps data rate. Workstation B receives this stream correctly. The ...
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5answers
3k views

Is rerouting possible in UDP?

So I am trying to understand routing for TCP and UDP segments. I have a couple of things that I am confused about: In TCP, is there any specification on how many packets would be dropped before a ...
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1answer
269 views

802.11 multicast buffering due to random back-off mechanism

I am trying to achieve periodic multicast with WAP (Wireless Access Point) [basically trying to stream real time audio data to multiple devices]. The regularity in the interval between successive UDP ...
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2answers
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UDP Sessions and Ephemeral Port Selection

I would like to ask community to help me finding answers to the following questions: According to RFC 6056 an operating system should pseudo-randomly select ephemeral ports for each transport layer ...
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1answer
295 views

Header checksum and pseudo IP header

In IP header we have header checksum field which is calculated at every hop because some of the fields in IP header like TTL changes in every hop. In TCP we calculate checksum on pseudo IP header + ...
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2answers
197 views

Hardware Implementation of Ports

What is the hardware implementation of a port and/or network socket? I understand that, at the lowest level, x86 uses opcodes such as IN and OUT when the data resulting from the instruction execution ...
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4answers
855 views

Why the combination of “TCP/IP” is more popular than “UDP/IP” [closed]

According to 7 Layers of the OSI Model, IP is located at layer 3 (Network), while TCP and UDP are located on layer 4 (Transport). Just for the sake of curiosity, why the combination of "TCP/IP" term ...
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1answer
466 views

Where in PCAP-NG does the Source/Destination IP address information reside?

I'm studying the pcapng file format, and I know that when wireshark reads a pcapng file, it tells you all sorts of information. I've been reading the pcap-ng format and I don't see anywhere in pcapng ...
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2answers
473 views

port 8820 - what is it?

I need to write a code, which communicates between 2 computers. I saw many people use port 8820 in their code when they want to communicate between computers. I know the term port but What is port ...
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1answer
2k views

UDP Over Ethernet - Where exactly and in what order will the UDP information show up in the payload of my Ethernet frame?

I need to capture UDP information coming to me via an Ethernet frame. I have a point to point connection by fiber with 1000BASE-X Ethernet. The information coming to me is in GMII format; which is ...
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1answer
251 views

Is it possible to successfully send a spoofed UDP header with a completely unrelated source IP?

I've read that many networks use ingress/egress filtering to eliminate the number of spoofed UDP packets sent and received by their network. Given that network provides have been much more diligent ...
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1answer
258 views

Client security using UDP

Introduction I am currently trying to build up a networking layer for Unity from scratch. Currently I am testing the communication via UDP using Node.js for the server and the client. However I guess ...
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2answers
520 views

Does implementing some level of reliability in UDP packets defeat its purpose over using TCP?

Considering UDP packets can get lost or arrive late to their target destination, does it make more sense to: Use a TCP socket for important messages & events (ex: in a game where a player gets ...
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3answers
550 views

How to differentiate between UDP traceroute packet and the normal data traffic?

I am a programmer and we can filter out the packets in the router to manipulate the IP or MPLS headers. My question is there any way to distinguish between UDP 1 byte traceroute data vs user traffic ...
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1answer
1k views

Is there any way a UDP checksum could be inconclusive of error detection?

If I am receiving data through UDP, with a checksum that checks out to show no data loss, is there a possibility that the checksum missed some errors. My data transmitted is split into 24-bits chunks ...
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4answers
277 views

Tcp reliabity handled at hardware level?

At work we are moving from a TCP to a UDP protocol for a kind of 3D engine because we have 1s hang when a packet is lost. Since our engine is not designed to handle packet loss nor out of order ...
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1answer
726 views

TCP error recovery

Consider two machines A and B, machine A sends 3 packets to B of sequence number 1, 2, 3 during transmission only packets 1 and 3 are received by B. Now B requests for packet 2, and machine A sends ...
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2answers
475 views

How does data encapsulation work in the TCP/IP stack?

As a UDP segment traverses down the stack, each layer adds a header. What occurs for this to happen? Does the kernel do a bunch stuff then add the header? I am particularly interested in the ...
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1answer
760 views

How does address resolution work with multicast, specifically IPv6?

If I want to send an IPv6 UDP multicast message, how does L3 to L2 address resolution occur? I think I understand ARP and how this same idea applies to unicast, but I am struggling to grasp the idea ...
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4answers
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PING port number?

Yesterday interviewer ask me what is port number for ping and which protocol ping use TCP/UDP. After interview I search on internet and found different different results someone says ICMP uses Port 7,...
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4answers
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What does a UDP connection timeout really mean?

Since UDP is a connectionless protocol, I'm confused by the setting on my Sonicwall Firewall for "UDP Connection Timeout". It's set at a default of 30 seconds -- but what exactly times out after 30 ...
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2answers
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How does the TCP/IP stack handle UDP checksum errors?

RFC 2460, Internet Protocol, Version 6 (IPv6) Specification, Section 8.1 Upper-Layer Checksums, states the UDP checksum is mandatory and any IPv6 receivers must discard UDP packets containing a zero ...
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2answers
43 views

Understanding the ways of communication in IP networks

I am trying to check my understanding about the ways of communication in IP networks. I would classify the ways of communication in IP networks into three generic types: The source requests name ...
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1answer
95 views

Looking for a lightweight reliable protocol directly built upon Ethernet utilizing jumbo frames? [closed]

I am looking for a lightweight reliable protocol utilizing Ethernet jumbo frames (for instance up to 9 KBytes). One side will be implemented on an FPGA without a CPU core (so simplicity needed) and ...
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1answer
395 views

UDP hole punching. How to listen to a port that is busy?

Good day everyone! I am developing a network application that is extremely time sensitive and having an intermediary server is not an option. Therefore, I decided to implement a udp hole punching ...
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1answer
629 views

Is UDP used in every TCP/IP connection?

I am confused on whether UDP and TCP work together, or are they completely separate protocols. So, UDP is used to allow multiplexing of different services on the same machine. So, essentially, for ...
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1answer
309 views

SNMP protocol MIBs & OIDs

I am trying to understand SNMP protocol. I have clear understanding how SNMP works on network level. We can send UDP request to device, but on this device snmpd should listen for incoming requests. ...
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2answers
2k views

IPERF TCP vs UDP

I had to determine UDP performance over multi-hop network , I used MAC Air over gigabit ethernet ( Thunderbolt). As is customary, TCP was tested and the gig over link was saturated ~900mbps, but ...
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4answers
714 views

Do subnet masks hinder the ability to listen to a UDP multicast?

I have a device connected to an ethernet switch, and my PCs NIC is connected to that switch as well. The device is sending multicast messages to 239.255.255.251 to which I am able to listen. My ...
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2answers
557 views

Types of packet loss

I am used to the term ICMP Ping Packet Loss but recently, I came across this other term UDP Jitter Packet loss I will like to know the difference between the two, and of what importance it is to ...
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2answers
176 views

The meaning of TCP port in the network context

When talking about ports, sometimes I read articles that state TCP port while others just say port. Are there some features that make TCP port different from other ports in the OS?
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1answer
35 views

How the hops and the subnets are influencing NATs and ports ?

I'm a beginner with networking, specifically linux networking, I have a question that I'll split into 2 parts : If I have an x number of hops inside the same subnet ( namely 192.168.1.x ) and my goal ...
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2answers
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How to find out TCP/UDP latency of your network?

Many people often suggest you to use ping command to find out your network latency. But it is false and a myth you often find in articles on Internet. ICMP ping was never designed to find out latency ...
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1answer
408 views

UDP and fragmentation calculation

Assume we have a ethernet link with an MTU of 1300 bytes, while an application want to send 5200 bytes of data. How many fragments do we transmitted ? i would say 5, to send 5200 bytes over a link ...
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1answer
1k views

How TCP hole punching works?

Is TCP Hole Punching similar to UDP hole punching?How it is established between "Peer A" and "Peer B" when both the peers are behind NAT? You can use Peer A and Peer B as example to make it easy to ...
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2answers
308 views

Do MSS/MTU violate the protocol stack layers independence?

We studied that the beauty of internet protocol suite layers is that each layer is responsible for a piece of the communication process. These layers provide services to adjacent layers and operate ...
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4answers
860 views

Is a unique TCP/UDP port assigned to a user?

I know that a user is assigned a routable IP to access internet so I was wondering if user is also assigned with TCP/UDP port too? I mean just like there is a specific IP of the destination server ...
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1answer
142 views

When last was the OSI model layer updated

since reading about the OSI model, which was created since 1984. My question is has there been any revision on the model. Or did the delegate who design the OSI model made it for everlasting. Thanks
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6answers
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When would one use UDP over TCP? [closed]

It seems TCP is quite a reliable service with error checking, end-to-end delivery assurance etc/, while UDP is a connectionless unreliable service. In what occasion would application engineers use ...
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2answers
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How does a layer-2 switch work with UDP?

If UDP and/or TCP send packets via IP to an Internet Protocol Address, how can a layer-2 switch forward these? Is this possible or do you need a layer-3 switch?
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1answer
261 views

Firewall seems to damage/delay packages

I have two networks communicating with each other through a transparent firewall. My problem is that the software using these networks is reporting that it's losing packages. The number of lost ...